Angiogenin is a 14 kDa, non-glycosylated polypeptide which is produced by several growing cell types including vascular endothelial cells, aortic smooth muscle cells, fibroblasts, and some tumours such as colon carcinomas, ovarian carcinomas, and breast cancers. Angiogenin has been isolated from a number of sources including normal human plasma, bovine plasma, bovine milk, and mouse, rabbit and pig sera.
Angiogenin is homologous to pancreatic ribonuclease and has distinct ribonucleolytic activity. The protein is able to induce new blood vessel growth; however, it has not been established what role the ribonucleolytic activity of angiogenin plays in angiogenesis induced by this protein.
The concentration of angiogenin in normal human plasma is 60-120 ng/ml. However the concentration of the protein is elevated in patients affected by various types of cancer, and inhibition of angiogenin is known to prevent human tumour growth.
As well as a potent stimulator of angiogenesis, angiogenin has been shown to possess a number of other activities. These include the ability to remove skin defects such as pigmented spots, modulation of immune responses, protection of polymorphonuclear leukocytes from spontaneous degradation, and microbicidal activity against systemic bacterial and fungal pathogens. Based on the known physiological functions of the protein, various angiogenin applications in medicine, dietary foodstuff supplements and cosmetics can be predicted.
However the use of angiogenin in such applications requires an efficient process for the preparation of the protein on a commercial scale from an appropriate source. It is an aim of a preferred embodiment of the present invention to provide such a process. This process may also be included as part of an existing process for purification of other components of milk products, such as lactoferrin, lactoperoxidase or growth factors.
All references, including any patents or patent applications, cited in this specification are hereby incorporated by reference. It will be clearly understood that, although a number of prior art publications are referred to herein, this reference does not constitute an admission that any of these documents forms part of the common general knowledge in the art, in Australia or in any other country.